I say, and with God's success: It is an expression of his annoyance at dealing with someone who is demanding a debt from him. However, if he says it without the need for assistance in demanding the debt, and that person is not openly committing a sin regarding the debt, then it is feared that it may be considered backbiting. If it is true, then there is no sin upon him; but if he is not demanding a rightful claim and is not truthful, he has sinned for slandering his Muslim brother and for backbiting.